Investigation of two coronal mass ejections from circular ribbon source region: Origin, Sun-Earth propagation and Geo-effectiveness

TL;DR

This study compares two similar coronal mass ejections originating from circular ribbon regions, analyzing their solar source characteristics, interplanetary evolution, and differing impacts on Earth's geomagnetic environment.

Contribution

It provides a detailed analysis of two CMEs with similar source regions but different geo-effectiveness, highlighting the role of magnetic configuration and propagation in space weather.

Findings

One CME caused a weak geomagnetic storm (Dst ≈ -20 nT).

The other CME resulted in a strong geomagnetic storm (Dst ≈ -119 nT).

Both CMEs originated from circular ribbon flares indicating fan-spine magnetic structures.

Abstract

In this article, we compare the properties of two coronal mass ejections (CMEs) that show similar source region characteristics but different evolutionary behavior in the later phases. We discuss the two events in terms of their near-Sun characteristics, interplanetary evolution, and geo-effectiveness. We carefully analyzed the initiation and propagation parameters of these events to establish the precise CME-ICME connection and their near-Earth consequences. The First event was associated with poor geo-magentic storm disturbance index (Dst $\approx$-20 nT) while the second event is associated with intense geomagnetic storm of DST $\approx$-119 nT. The configuration of the sunspots in the active regions and their evolution are observed by Helioseismic and Magnetic Imager (HMI). For source region imaging, we rely on data obtained from Atmospheric Imaging Assembly (AIA) on board Solar Dynamics Observatory (SDO) and H$\alpha$ filtergrams from Solar Tower Telescope at Aryabhatta Research Institute of Observational Sciences (ARIES). For both the CMEs, flux rope eruptions from the source region triggered flares of similar intensities ($\approx$M1). At the solar source region of the eruptions, we observed circular ribbon flare (CRF) for both the cases, suggesting fan-spine magnetic configuration in the active region corona.